Method of making molded products



106. COMPOSITIONS, Examiner COATING OR PLASTIC. M.

a 4 1 U Patented Oct. 8, 1935 v 2,016 796 UNITED STATES PATENT OFFICEMETHOD OF MAKING MOLDED PRODUCTS Arthur S. Brock and Carl F. Meinzer,Chicago,

Ill., assignors, by mesne assignments, to Wallace L. Caldwell,Birmingham, Ala.

No Drawing. Application July 25, 1934, a Serial No. 736,908 i 10 Claims.(Cl. 18-475) This invention relates to the manufacture of (c) Whenpulverized slag is used with an alkali molded products by the use ofsteam curing unsilicate with the addition of the concrete admixdersuperatmospheric pressure. It refers partictures hereinbefore mentioned,a further reducularly to the use of a mixture of water-granulated tionin the cost of the combined cementing ma- 5 slag, preferably inpulverized or powdered conditerials is effected over the combination setout in g Q' tion and an alkali siligatg preferably selected fromparagraph a.

the group consisting'of sodium silicate and lpo- The preferredproportions which may be used tassium silicate as a cementing materialwit or in making concrete products according to our without the additionof small amounts of pulver invention are as follows: 1 ized lime,silica, clay, talc, diatomaceous earth, m

l bentom e, asbestos, asbestm' e, .or smar admix Pamb ures I Material gAmong the benefits secured in steam curing under pressure may bementioned: pulverized Slag w 1. The compressive strength usuallyobtained gr e el g r gates)- a; 15 through a slow process coveringfourteen to 3:3,??? ca 4 twenty-eight days or more, is obtained in eightdmixture $4 to twelve hours of steam curin' g under pressure.

2. The volume change or shrinkage of products The time and pressure ofsteam curing the 20, cured by the usual methods during the dr i g- 9above mixture to produce a strength equivalent period, is greatlyreduced or practically elimito Ordinary concrete is as follows: natedwhen steam curing under pressure is used. 1 3. Products which are steamcured under pressure dry out rapidly to a practically constant TimePressure amount of moisture in about forty-eight hours 5 after removalfrom the kiln. 1st hour 0 to 75 pounds per square inch.

Due Pa cqmbinaiion of the above three triifttiaa'iaaiasezz: iiogfiilttltfit'riitfiitttta characteristics it is possible to obtainproducts mately constant. when steam cured under pressure which may be mmums Persqum mch I 3Q delivered about three days or even less, aftercasting in the molds. The above proportions and pressures are given Inaddition to the above mentioned benefits of for purposes of illustrationand in no sense are steam curing, mixtures of granulated slag andintended to limit our invention. It is also to be alkali silicates whensteam cured under pressure, understood that variations of these itemsmay result in structures whose strength is out of all be made over awide range for various propor- 35 i proportion to the amount of alkalisilicate used. tions and still produce satisfactory results. Howi i Inother words, the alkali silicate appears to funcever, the proportion ofalkali silicate in solution tion in the nature of a catalyst to causethe slag will never exceed tweny per cent; and prefer- 1 to havecementing action, which is developed only ably not over ten iefieirt byweight of the total t 40 in steam curing under superatmosphericpressure. weighthf the smate'ann granulated slag of all 40 In addition,the following benefits are also ingrading, including the pulverized slagpresent herent in our process: in the molded product.

(a) The cost of the cementing material which The pulverizf edslag usedin the hereinbefore consists of pulverized slag and an alkali silicate,described mixture has substantially the same will be much less than thecost of the usual Portfineness as ordinary Portland cement or about 45land cement thus effecting a decided reduction in ninety per centpassing a 200 mesh screen. Howthe cost of materials. ever, it can varyfrom this fineness and still be (b) When our invention is used with slagagused in our invention. The slag used herein is gregates (especiallygranulated slag) either fine water-granulated sla derived from a moltenBr'coar'se' or both, there is a cementing action beblast furnace slagranulated in the presence of 50 tween the alkali silicate, concretemixture if used, water. To produce pulverized or powdered slag and theslag aggregates which clearly increases the water-granulated slag issubjected to a conthe strength and performance of these productsventional grinding or reducing process. The slag over those made withPortland cement and slag used may have a variety of chemical ingredientsaggregates. but it should preferably have a predominant 66 amount ofsilicates and lime. The alkali silicat es used may have the followingproperties:

NazO or K20 8.9% $210: 28.7% H2O 62.4% Baum 41 Weight per gallon, poundsapproximately 11.2

It is to be understood, however, that this solution can vary widely fromthese properties and still be used in our invention and, further, thatthe invention may be practiced by using the powderedsilicates in placeof the iolution.

Molded products made in accordance with the present invention and basedon the formula given in the specific example have developed structuralstrength in excess of 5,000 pounds per square inch. In addition, bysuitable variations in proportions, strengths in excess of 10,000 poundsper square inch may be obtained. Obviously, this strength is out of allproportion to the amount of alkali silicate used and, hence, it isbelieved that the silicate functions in the nature of a catalyst inimparting cementing properties to the slag. This hypothesis is basedupon tests wherein various ingredients of a cementing mixture have beenprepared and the resultant products tested. In one case the alkalisilicate was omitted and in the other the pulverized slag was omittedand in each case substantially no appreciable compressive strength couldbe measured in a testing machine. Further, tests have been conducted ofalkali silicatepulverized slag mixtures cured in a conventional mannerand no appreciable compressive strength has been obtained which can bemeasured in a conventional testing machine.

If desired, the alkali silicate and pulverized water-granulated slag maybe used in conjunction with sand or gravel aggregates and the resultantmass steam cured in the hereinbefore described manner. A heavier, moredense resultant product will obviously be obtained than if slagaggregates are used.

By the expression steam curing under superatmospheric pressure, we wishto include any other process by which there is obtained a curing in thepresence of moisture at a temperature of 212 F., or greater.

By the expression admixture as used in the specification and claims, ismeant such materials as pulverized lime, silica, clay, t a .l g,diatomaceous earth, bentor'fitE asbestos, asbestine, or other We claimas our invention:

1. A process of making molded products comprising mixing pulverized slagand alkali silicate, and steam curing the mixture under superatmosphericpressure.

2. A process of making molded products comprising mixing pulverizedwater-granulated slag and alkali silicate, and steam curing the mixtureunder super-atmospheric pressure.

3. A process of making molded products comprising mixing pulverizedwater-granulated slag and sodium silicate, and steam curing the mixtureunder super-atmospheric pressure.

4. A process of making molded products comprising mixing pulverizedwater-granulated slag and potassium silicate, and steam curing themixture under super-atmospheric pressure.

5. A process of making molded products which comprises, mixing slagaggregate, an alkali silicate and pulverized water-granulated slag, andsteam curing the mixture under super-atmospheric pressure.

6. A process of making molded products which comprises, mixingpulverized, water-granulated slag, an alkali silicate and an admixture,and steam curing the mass under super-atmospheric pressure.

'7. A process of making molded products comprising, mixing pulverizedwater-granulated slag and an alkali silicate taken from the groupconsisting of sodium silicate and potassium silicate, and steam curingthe mixture under super-atmospheric pressure.

8. A process of making molded products comprising mixing pulverizedwater-granulated slag and an alkali silicate selected from the groupconsisting of sodium silicate and potassium silicate in an amount lessthan 20% of the total mass and steam curing the mixture undersuper-atmospheric pressure.

40 9. A process of making molded products com-

